I. Field of the Invention
This invention relates to a windshield wiper assembly for operation in cold weather and, in particular to a heated windshield wiper assembly having a heating element disposed in the wiper blade support structure which is actuated and deactuated according to the temperature of the ambient air and the heating element.
II. Description of the Prior Art
Past known devices have provided various solutions for supplying heat to the wiper system of a motor vehicle in order to minimize icing of the wiper blade and system. These include embedding the heating elements in the flexible wiper blade in order to supply heat to the blade. However, by including the heating element within the wiper blade, the blade does not flex properly when in operation because of the rigid nature of the heating element. Moreover, replacement of the blade, which should be accomplished approximately every twelve months, is expensive since the heating element is discarded along with the wiper blade.
In order to permit less costly replacements to be utilized in a heated wiper system, the heating element is disposed behind a backing member of the blade. This development allows standard wiper blades to be utilized in the wiper system thereby reducing the cost of replacement.
However, the foregoing solution was still inadequate because with either modification the heat produced when the element was left on for excessive periods of time quickly deteriorated the rubber blade. In addition, overheating may cause damage to the wiper system itself. In order to overcome this deficiency, a heat sensitive control was provided in close contact with the heating element. The control unit deactivated the heating element upon reaching a predefined temperature. This modification, however, still required manual actuation of the heating element by the vehicle user. Moreover, no means are provided for overriding the control unit in order to allow continuous heating of the wiper system when conditions required. Finally, because the heat control unit is disposed separately from the heating element, the possibility of overheating remains.